Socket庫在C++中的并發模型

在C++中，使用socket庫可以實現多線程并發模型。以下是一個簡單的示例，展示了如何使用C++的socket庫和線程庫實現并發服務器：

#include <iostream>
#include <thread>
#include <vector>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>

const int PORT = 8080;
const int BUFFER_SIZE = 1024;

void handle_client(int client_socket) {
    char buffer[BUFFER_SIZE];
    while (true) {
        ssize_t bytes_received = recv(client_socket, buffer, BUFFER_SIZE - 1, 0);
        if (bytes_received == 0) {
            break;
        }
        buffer[bytes_received] = '\0';
        std::cout << "Received from client: " << buffer << std::endl;
        send(client_socket, buffer, bytes_received, 0);
    }
    close(client_socket);
}

int main() {
    int server_socket = socket(AF_INET, SOCK_STREAM, 0);
    if (server_socket == -1) {
        std::cerr << "Error creating socket" << std::endl;
        return 1;
    }

    struct sockaddr_in server_addr;
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = INADDR_ANY;
    server_addr.sin_port = htons(PORT);

    if (bind(server_socket, (struct sockaddr *)&server_addr, sizeof(server_addr)) == -1) {
        std::cerr << "Error binding socket" << std::endl;
        return 1;
    }

    if (listen(server_socket, 5) == -1) {
        std::cerr << "Error listening on socket" << std::endl;
        return 1;
    }

    std::vector<std::thread> threads;
    while (true) {
        struct sockaddr_in client_addr;
        socklen_t client_addr_size = sizeof(client_addr);
        int client_socket = accept(server_socket, (struct sockaddr *)&client_addr, &client_addr_size);
        if (client_socket == -1) {
            std::cerr << "Error accepting client connection" << std::endl;
            continue;
        }

        threads.push_back(std::thread(handle_client, client_socket));
    }

    for (auto &thread : threads) {
        thread.join();
    }

    close(server_socket);
    return 0;
}

在這個示例中，服務器首先創建一個socket，然后綁定到指定的端口上。接下來，服務器開始監聽客戶端連接請求。當接收到一個連接請求時，服務器會創建一個新的線程來處理客戶端的請求。這樣，服務器就可以同時處理多個客戶端連接，實現了并發模型。